1. Field of the Invention
The present invention relates to a light source, and more particularly, to an LED surface light source capable of obtaining high power output and uniform light.
2. Discussion of the Related Art
Light emitting device (LED) is a device that emits light using an electrical signal. The LED is driven at low power and widely used in small-sized optical parts.
FIG. 1 is a view of an LED according to the related art.
Referring to FIG. 1, an LED includes an LED n-type layer 12, a light emitting layer 13 and an LED p-type layer 14, which are sequentially formed on a substrate 11.
The LED p-type layer 14 is in contact with an anode 15 and coupled to a positive (+) power supply voltage. The substrate 11 is in contact with a cathode 16 and coupled to a negative (−) power supply voltage.
In such an LED, if electrons move due to a voltage difference occurring when a voltage is applied to the anode 15 and the cathode 16, energy change occurs within material of the light emitting layer 13. In this manner, the light is emitted.
Here, the light from the light emitting layer 13 is radiated in omni-direction. Therefore, a reflector 17 is disposed around the LED so as to focus the light in one desired direction.
The light reflected in a predetermined direction by the reflector is focused and outputted by a condenser lens 18.
When the LED is used as a light source, the LED may be used in a type of one module or the integrated LEDs may be used.
FIGS. 2A and 2B are a perspective view and a top view of the conventional LED used as the surface light source, respectively.
As shown, a plurality of LED modules 21 for the surface light source are arranged in horizontal and vertical directions.
However, in the case of the conventional LED surface light source, size of the LED module 21 is so large that a small number of the LEDs are condensed in unit area. As a result, it is difficult to obtain the high power output.
Also, since the gap 22 between the LED arrangements is wide, the light distribution is ununiform and the interconnection of the LEDs is complex.
Accordingly, the conventional LED surface light source has a drawback in that it is difficult to use it as the light source of the projection system requiring the small scale.